Warp knitting machine tensioning device



K Dec. 7, 1954 T. F. scHwANoA E-r-AL WAR? KNITTING MACHINE 'rENsIoNING DEVICE Filed Aug. 19, 1952 3 Sheets-Sheet 1 A mw luy@ MAWAO m. www N. www mm w/w mv. ww 2.6i. EN w RM a UN @a mm mW .wwq\\ Mc wm Q W.. NGE

HC Mf ATTORNEY De@ 7, 1954 T. F. scHwANnA ETAL 2,696,094

wAEP KNITTING MACHINE TENsIoNING DEVICE Filed Aug. 19, 1952 3 Sheets-Sheet 2 IN I "EAU URS. THEODORE F SCHWANDA CLARENCE J. BROWN ff. C. @M

ATTORNEY Dec. 7, 1954 T. F. scHwANDA ETAL 2,596,094

wARP KNITTING MACHINE TENsIoNING DEVICE Filed Aug. 19, 1952 3 Sheets-Sheet 5 NGE - INVENTORS. THEODORE E SCHWANDA BY CLARENCE J. BROWN ATTORNEY United States Patent O WARP KNITTING MACHINE TENSIONIN DEVICE Theodore F. Schwanda and Clarence J. Brown, Bangor, Pa., assignors to Blue Ridge Textile Co., Inc., Bangor, Pa., a corporation of Pennsylvania Application August 19, 1952, Serial No. 305,226

17 Claims. (Cl. 66-86) The present invention relates to warp knitting machines and more particularly to yarn tensioning and beam brake releasing devices associated therewith. The present invention is a continuation in part of copending U. S. patent application Serial No. 85,106, filed April 2, 1949, now Patent No. 2,651,930.

In warp knitting machines, the yarns are drawn from the beams or banks of reels as they are required for each knitting cycle by the movement of the knitting mechanism. To avoid intermittent tugs upon the yarns which would increase the danger of breakage and which would result in irregularities in the knitting operation and in the fabric itself, various means are employed to provide a smooth yarn feed. These means generally comprise devices forl resiliently supporting the yarn and responsive `to the strain placed on the yarns as they pass from the reels to the knitting mechanism to release and control the extent of rotation of the reels. Improvements in the resilient yarn support between the reels and the knitting needles and the means for controlling the release of the `reel braking mechanism are the subject matter of the present invention.

The resilient yarn support, which is sometimes termed a yarn pilot or guide rod, but which is herein referred to as a tension rod, is rendered resilient by suitable means and, as the yarns pass over its polished surface, is responsive to the strain placed on the yarns in the course of each knitting cycle to release the reel braking mechanism. In the operation of the machine, the resiliently supported tension rod and the associated reel braking mechanism maintains a relatively even tension in the yarn thereby avoiding irregularities in the operation and in the fabric. When the machine is stopped for any reason, it has been found that, after again commencing operation, a marking in the fabric will reveal the line at which such stoppage occurred because, upon stopping, a certain amount of slack is created in the yarns and the tension rod is incapable of maintaining the same uniform tension therein. These markings in the fabric are generally termed stop markings.

ting cycle in the appearance of the fabric.

An object of the invention has been to provide improved means for resiliently supporting the tension rods of a warp knitting machine and for minimizing or preventing the formation of stop markings.

Another object of the invention has been to provide means for anticipating and cushioning sudden application or release of the tension upon the yarns.

A further object of the invention has been to provide means for automatically adjusting the reel brake mechanism release time with changes in the amount of yarn on the reels, thereby insuring a uniform feed of the yarn as the diameter of the supply on the reels decreases.

Other and further objects, features and advantages of the invention will appear from the following description.

In accordance with the invention, a warp knitting machine having a resiliently displaceable tension rod responsive to the variations of the pull of the yarn flowing-over it is provided with yarn tension sustaining means associated therewith for urging the tension rod against the yarns. This sustaining means includes an enclosed chamber, means for introducing a fluid under a first predetermined pressure into the chamber and means, such as a piston and connections therefrom to the tension rod, associated with the chamber and responsive to the pres- When the mechanism begins operating, this difference in yarn tension is reflected during the first knitsure of the uid therein, means for controlling the operation of the machine and means responsive to such controlling means for introducing the uid under a second predetermined pressure into the chamber. Also in accordance with the invention, means operatively connected with the sustaining means are provided for releasing the yarn reel braking mechanism in response to pull applied to the yarns and for a time interval related to the supply of yarn on the reels.

The invention will now be described in greater detail i with reference to the appended drawings in which:

Fig. l is a side elevational view of the tension rod support means and the beam or reel with its brake releasing means in accordance with the invention;

Figs. 1a and 2a are diagrams explanatory of the operation of the mechanism shown in Fig. l;

Fig. 2 is an enlarged sectional View ofthe means according to the invention for applying the desired tensioning forces to the supporting means for the tension rod;

Fig. 3 is a schematic view of the control and pressure system for maintaining proper yarn tension during machine operation and for varying the tension upon stopping of the machine; and

Fig. 4 is a circuit diagram of a motor control system irritable for use with the control and pressure system of The warp knitting machine to which the invention is shown applied will contain all of the usual instrumentalities provided in such machines. However, only those parts related to and cooperating with the invention have been illustrated in the drawings. For further details as to the construction of a warp knitting machine and its general mode of operation, reference may be had to prior patents and publications, including the patent to S. I. Thomas No. 2,464,468 granted March 15, 1949, and the book, entitled Tricot Fabric Design, by Thomas Johnson, publlgished by the McGraw-Hill* Book Company, Inc., in 4 Referring now to the drawings and more particularly to Fig. l thereof, there is shown a tension rod 10 which is the conventional polished rod used in warp knitting machines and which is generally about one inch in outside diameter. Tension rod 10 runs the length of the machine and is arranged parallel to the axis of beam or yarn supply reels 11. The yarn supply reels 11, only one of which is shown in Fig. 1, supply a plurality of yarns to the machine knitting mechanism, the number of yarns per inch of width depending upon the character of the fabric to be formed. The yarns, in their paths from the reels to the knitting mechanism, are drawn over the tension rod 10. One of the yarns, designated as 12, is shown in F ig. 1.

Tension rod 10 is carried by two or more rock arms 13 which are supported by and which pivot about the axis of a pivot rod 14 which may, in turn, be suitably supported on reel supporting extensions 15 of the machine frame. Each of the rock arms 13 is provided adjacent one end thereof with a hole 16 adapted to accommodate a guide rod 17. Each guide rod 17 is rigidly secured to the machine frame by an anchor rod or pin 18.

The yarn reels 11 are mounted for rotation with a shaft 19 suitably journaled in the machine frame. A gear 20, also rigidly mounted on the shaft 19, is arranged to mesh with a gear 21 rigidly mounted on a shaft 22 journaled for rotation in the machine frame. Shaft 22 also carries a brake drum 23 securely affixed thereto. A pair of arcuate brake levers 24 and 25 are arranged about the drum 23. One end of each of the levers 24 and 25 is pivotally attached to a bridge member 26. Each of the levers 24 and 25 is provided with a notch for retaining a respective one of brake shoe lever bolts 27 and 28. The bolts 27 and 28 each carry a respective one of brake shoes 29 and 30. i

The brake shoes 29 and 30 are-adapted to engage the outer surface of the brake drum 23 to prevent rotation of the drum 23, the shaft 22 and the gear 21, thus also preventing rotation of gear 20, shaft 19 and yarn reels 11. The brake shoes 29 and 30 are normally held in engagement with the brake drum 23 through a springv 31 which intercouples and urges toward each other the ends of levers 2d and 25 remote from the member 26. A pair of brake release arms 32 Vand 33 are pivotally 'attached to the machine trame extension 15 by means of pins 34 and 35. The ends of arms 32 and 33 adjacent spring 3l are provided with threaded studs 36' and 37, respectively. Stud 36 is received in a threaded hole provided in the end of lever 2li adjacent the spring 31, while stud 37 is received in a similar-hole provided Vin the lever 25. The arrangement is such that when the ends of arms 32 and 33 remote from spring 31 are rocked toward eachother about-therespectiye pins 34andf35, the levers 24 and 25 willl pivot awayfrom the drum 23 and against the tension provided by spring 31. When this occurs, the brake shoes 29 andy 30' will no longer hold the drum 23 and rotation of the yarn reelsllll' will be permitted;

Release ofl the brake mechanism topermit delivery of yarn is eitected through a pushk rod 3S having a bifurcated end comprisingin'clined fingers 39 and 40. Fingers 39and- 4@ are adapted to engage, respectively, rollers 41 and d2 provided on respective ends of arms 32 and 33. When rod 38 is caused to move to the left in Fig. l, ngers 39 and 40 engage rollers 41 and 42, respectively, thereby rocking the adjacent ends of arms 32 and 33 toward each other to release the brake and permit delivery of yarnfrom the-reels 11.

An elongated slot liii-is provided in rod 38 adjacent the bifurcated end thereof. A guide bolt 44 carried by a block 43 mounted on the extension 15 extends through the slot 431 to guide-the arm 38 in its reciprocatory movement.

The other end of arm 38 is provided with an elongated slot 46 into which extends a bolt 47 carried by a block 4S. The block 48 is aixed to the arm 13 and pivots therewith about the rod 14. When a pull is exerted on the yarns by the knitting mechanism, the arms 13 are rotated about the rod 14 in a clockwise direction because of the force exerted by the yarns on the tension rod 1li.

The motiony imparted to arm 13 causes block i8 to rock similarly. This motion is transmitted to the arm 33 through bolt 47 acting in slot 46, therebyv causing arm 38 to travel toward the left and release the brake mechanism as described above. Release of the brake permits delivery ot yarn from the reels 11 to the knitting mechanism, thus relieving the pull on the yarns and allowing the arm lf3: tov rock int arcounterclockwise direction about the pivotv rod 14, thereby allowing the spring 31 to operatethe brake mechanism and prevent further delivery of yarn.` The counterclockwise rotation of arm 13 is effected in response to the decreased pull of the yarns through a tensioning mechanism to be described hereiny after.

lt will. be observed that adjustment of the relative angular positions of thearrn 13 and the block 48 about the pivot rodi` 14 will. permit release of the brake mechanism at any desiredy leftward displacement of the arm 33 from its position when no pull is applied to the yarns. For reasons which will be discussed hereinafter, when the reels are substantially fully loaded with yarn, the brake mechanism is preferably not fully released to permit delivery of-yarn until a substantial leftward displacement ofthe arm 38'has taken place.

As was pointed out above, the tension rod 1li is supported by two or more arms 13. One or more of the arms 13 may be associated with a brake mechanism as described. ln general, however, it will be found that a single brake mechanism associated with a single one of the arms 13 will provide satisfactory operation. lt should be understood that the particular brake mechanism shown and described is intended solely for the purpose of illustration as many other braking mechanisms could be employed.

Disposed about the guide rod 17 and above the upper side of each of the arms 13 there is provided a sleeve Si) having a llange 51 at its lower end arranged to ride on the arm 13 and a flange 52 at its upper end arranged to press against the lower end of an annular piston rnernber S3.

As best shown in Fig. 2, a cylinder barrel 54 is arranged about the piston member 53. The cylinder S4 is provided with a central portion 55 arranged between the inner surface of the piston 53 and the guide rod 17. Both the piston 53 and the guide rod 17 are slidable with respect to the cylinder 5d. Adjustable thumb nuts 56 and 57 are threaded on the upper end of guide rod 17 to provide for adjustment of the position of the cylinder 5d till on the guide rod. The cylinder is urged upwardly against the bottom of nut 57 and its position along the 'rod' may be varied when desired. Packing 58 is provided on top of piston 53 to insure a duid-tight t of the piston 53 and cylinder 54. An inlet 59 is provided in the top of cylinder 54 to admit a compressible fluid such as air into the interior of the cylinder. While other fluid substances may be employed, for convenience the invention will be described hereinafter in connection with air.

When air under suitable pressure is admitted into the cylinder 54, the piston 53 is urged downward by the pressure. The piston 53 will descend until the downward pressure of the air is balanced by the force exerted on the bottom thereof by the yarn tension acting through the tension rod 10, the arm 13, the ilange S1, the sleeve Si) and the flange 52. During normal operation of the machine, the pressure Within the cylinder 54 is maintained substantially constant. The pressure is preferably maintained at some value within the range of about l0 to 30 p. s. i. A pressure of about 17 p. s. i. has been found quite satisfactory when the length of the lever arm 13 to the right of rod 14 in Fig. l is about twice the length of the lever arm to the left of the pin 14. A spring member in addition to or in lieu of the sleeve 50 may be provided for connecting the piston 53 and the arm 13 to absorb surges of pressure.

When the knitting mechanism pulls down onl the yarns, the arms 13 Will rock, as described, causing the piston 53 to rise within the cylinder 54, raising the air pressure therein to balance the increased upward force. The brake mechanism will be released, as described, permitting delivery of yarn. As a result, the pull on the yarns will be decreased, allowing the piston to descend to its original position under the action of the air pressure and again actuating the brake mechanism. When yarn is not being pulled, the downward pressure exerted on the piston and hence the upward force exerted on the yarn by the tension bar 1t) will be determined by the pressure of the air supplied to the cylinder 54.

The distance between the axis of rotation of the reels 11 and the point at which the yarn 12 leaves the supply is designated R in Fig. l. As the supply of yarn decreases, this distance decreases. At a decreased length it is designated r. The actual movement of the tension bar 10 as the knitting mechanism draws yarns from the reels 11, i. e., the length of the arcuate path described thereby about the pivot rod 1li, is substantially inde pendent of the amount of yarn on the reels. However, the extremities of this arcuate path will be shifted downwardly as the supply of yarn diminishes. Thus, if the arc R of Fig. la denotes the path described by the tension rod 10 when yarn having a radius of R is present on the reels 11, the arc r' might denotethe path described when yarn having the smaller radius r is present. Similarly,

' it the line R of Fig. 2a represents the travel of the arm 38 when yarn with a radius R is present on the reels 11, then the line r might represent the travel of the arm 38 when yarn with a radius r is present on the reels 11. The above described shifting of the arcuate path of tension rod lib will take place automatically. Thisis due to the fact that the position ot' piston 53 within cylinder 54 will vary as the amount of yarn on the reels decreases. The pressure of the air Within the cylinder will remain constant under normal operating conditions but the amount of air present in the cylinder at any time will be determined by the position assumed by the tension rod lt) when the yarn tension is balanced by the pressure of the air acting on the piston.

It will be observed that if the brake mechanism is not released until a considerable portion of the distance R has been traveled by the arm 38, then the brake mechanism will be released for a greater time interval when the travel corresponds tothe line r because, even though the lines R and r are substantially the same length, the brake mechanism will be released nearer the start of the travel r. The condition is desirable since it is evident that the brake must be released for a longer interval to feed the same amount of yarn with a short radius as with a long radius. It will be noted that the normal tension applied to the yarn will be that determined by the air pressure irrespective of the changes effected by diminishing yarn supply. It should be understood that the arcs R and r' and the lines R and r" are shown to illustrate the operation of the machine and are not intended to represent actual or relative displacements.

4 as, for example, 100

In order to prevent the formation of stop marks in the knitted material, it is necessary that the slack in the yarns be taken up when the machine is stopped. This may be accomplished by providing additional air pressure in the cylinders 54 when the machine is being stopped, thus causing the pistons 53 and the sleeves 50 to descend and rock the arms 13 in a counterclockwise direction about the pivot rod 14 thereby to rock the tension bar upward. It has been found that pressures lying within the range of about 20 to 30 p. s. i. are satisfactory for this purpose. Preferably, the increase 1n air pressure in cylinder 54 and the stopping of the knitting machine are correlated so that a smooth transition from operation to a stopped condition is achieved. Similarly, it is desirable that the starting of the machine and the concurrent reduction of air pressure in cylinder 54 be correlated. Suitable apparatus to achieve these features will be described hereinafter.

In the usual type of warp knitting machine, there are generally provided two tension rods, one for each of two beams or banks of reels, each tension rod being supported by three rock arms. Each rock arm should be provided with a tensioning device comprising a piston and cylinder and associated apparatus. However, only one rock arm for each tension rod need be provided with a brake and with the yarn tension responsive brake releasing mechanism.

In Fig. 3, there is illustrated a control and supply system for providing a supply of compressed air to each of the three rock arm cylinders required for the three rock arms usually provided for one of the beams in a warp knitting machine. The cylinders 70-72 shown in Fig. 3 correspond to the cylinder 53 and may be provided with pistons and associated connections to the tension rod in the same manner as shown in Figs. l and 2. The cylinders 70-72 are provided with compressed air supply pipes 70-72, respectively, each of which is connected to a feeder pipe 76.

Compressed air under a relatively high pressure such p. s. i., is supplied from a compressor 77 through a feeder pipe 78 to feeder pipes 79 and 80, each of which provides compressed air to a control system for the tension rod of one of the machine beams. The control system fed by the pipe 80 is not shown in the drawings but may be identical to the one illustrated in Fig. 3. The pipe 78 is provided with a valve 81, a strainer 82 and a pressure responsive switch 83. The switch 83 is provided to shut off the knitting machine driving motor in case of failure of the compressed air supply.

The pipe 79 is provided with a T connection 84 to divide the air supply between a run branch 85 and a stop branch 86.

The run branch 85 is provided with an adjustable pressure regulating valve 87 having a pressure gage 88. Valve 87 drops the air pressure in the branch 85 to a suitable value .for supplying the cylinders 70-72 during machine operation. This pressure might be, for example, about l p. s. i. The air under reduced pressure in branch S5 is supplied to a port C of a three way solenoid controlled valve 89. The solenoid for valve 89 is indicated at 89. The low pressure side of the branch 85 is also provided with a reservoir tank 90 and a pressure stabilizing relief valve 91. The function of tank 90 is to stabilize the air pressure while the machine is running.

The stop branch 86 is provided with an adjustable pressure regulating Valve 92 having a pressure gage 93. Valve 92 drops the air pressure in the branch 86 to a suitable value for supplying the cylinders 70-72 when the knitting machine is being stopped. This pressure might be, for example, about 25 p. s. i. The low pressure side of branch 86 is connected to a port B of the three way valve 89. Intermediate the valves 92 and 89, there is provided in the branch 86 a speed valve 94 which controls the rate at which the stop air enters the cylinders 70-72.

The third port A of the valve 89 supplies air to the feeder pipe 76 through a speed valve 95. Valve 95 is provided to control the rate of air leaving the cylinders '70-72 when the machine is starting and the air pressure must be reduced from the stop value to the run value. The speed valves 94 and 95 are preferably employed in connection with slow speed knitting machines and may be eliminated with high speed machines.

As will be described in greater detail in connection with Fig. 4, the valve 89 is under control of the solenoid 89'. When the knitting machine is operating and it is desired to supply air from branch to `the cylinders '70-72, ports C and A are open and port B is closed. When the machine is to be stopped, ports B and A are opened and port C is closed. In order to prevent the formation of stop marks, air pressure from branch 86 to the cylinders "/0-72 is maintained during the interval of stoppage. When the machine is to be started, port B is closed and port C is opened to reduce the cylinder pressure to the run value. The high stop pressure in pipe 76 and cylinders 70-72 is relieved by means of the relief valve 91 which is set to drop the pressure in the system to that desired on the low pressure side of valve 87.

When speed valves 94 and 95 are employed, the changes in air pressure upon stopping and starting are gradual so that the corresponding changes in yarn tension are effected gradually. This is desirable when the associated changes in speed of the knitting machine take place gradually.

It has been found desirable to delay stopping of the knitting machine motor for a predetermined time interval during which stop air pressure is applied to the cylinders 70-72 and also to the cylinders provided in connection with the other beam. Thus the desired additional tension is applied to the yarns before the machine is stopped. In a warp knitting machine in which the driving motor is not braked to a stop, the time delay feature is not as necessary and may, in some cases, be dispensed with. In a warp knitting machine in which the driving motor does not come up to speed very rapidly, it is desirable that reduction of pressure in the cylinders from the stop to the run value be delayed. A suitable motor control circuit embodying these time delay features is illustrated in Fig. 4.

Referring now to Fig. 4, an electric motor is provided for driving the warp knitting machine. Motor 100 is provided with 3 phase A. C. power through supply conductors L1, L2 and L3 and a magnetic starter 101. The circuit of Fig. 4 also comprises a push button station 102, an auxiliary relay 103, timer relays 104 and 105, solenoid 89 and a solenoid 89, the latter solenoid being intended to operate a valve corresponding to the valve 89 of Fig. 3 but included in the air supply and control system for the other beam.

When the start button of station 102 is pressed, the relay 103 is energized through a circuit extending from lines L1 to L3 and including the start and stop contacts of station 102. When energized, relay 103 locks up through one of its own pairs of contacts. The coil of timer relay 104 is energized through another pair of contacts of relay 103. Relay 104 is provided with a pair of contacts included in the contact coil circuit of starter 101. The contacts of relay 104 are closed when the coil thereof is energized, thereby operating starter 101 and applying power to motor 100.

Energization of relay 103 also closes an energizing circuit for the coil of relay 105. The latter relay is of the slow-to-operate type so that the contacts thereof do not close until a predetermined time interval after oper ation of the start button. The contacts of relay 105 are included in the energizing circuits of solenoids 89 and 89". When the contacts of relay 10S close, solenoids 89' and 89 cause their associated three way valves to operate to the positions in which the air pressure in the cylinders drops from the stop value to the run value. It will be seen, therefore, that the motor 100 is brought up to or near its operating speed before the air pressure is reduced and the tension provided by the tension bars is relaxed.

When the machine is to be stopped the stop button of station 102 is pressed, opening the energizing circuit of relay 103. This results in deenergization of relay 105, whereby solenoids S9 and S9 are deenergized and return to their normal positions in which the associated three way valves apply the stop air pressure to the cylinders. However, stopping of motor 100 is delayed for a predetermined time interval because relay 104 is of the slowto-release type. The energizing circuit for the coil of relay 104 is opened when relay 103 is released, but the coil of starter 101 is not deenergized until the contacts of relay 104 open. Thus stop air pressure is applied to the cylinders before power is removed from the motor 100.

The contacts of pressure switch 83 may be included in :managen :the energizing circuit y'of lthe coil of starterltll to stop .motor ltlupon a failureof'thecompressed air. supply.

The foregoing ris but one example of -the application .of the invention. Variousmodifications thereofiwilloccur to -those skilled in the ;art without-departing from the spirit and scope of the .invention as set forth in ythe 4appended claims. Forexample, in various types of Warp knitting machines, different arrangements .for supporting `the tension rodsare toibefound. Similarly, the shape-'and location of the supportingrock arm and of `the beam brake mechanism differs in differenty machines. lt is apparent, however, that the invention maybe incorporated in the several types of warp knitting machines.

What is claimed is:

l. In a warp knitting'machine/havinga resiiiently dis- 'placeable-tension rod responsive to variations of the pull of the yarns flowing over'ityarntension sustaining means 4arranged to urgesaid tension-rodlyieldinglyfagainst the yarns; said sustaining meansiincluding an enclosed chamber, meansffor -introducinga fiuidfun'der afirst predetermined pressure into said chamber, means associated with said chamber and responsive to thepressure of the iiuid -therein, and connections `interconnecting ysaid pressure responsive meansiand'said tensionrod; means for controlling operation ofthe machine; and'means responsive to said controlling means for introducing saidifluid under a second predeterminedpressureinto said chamber.

2, In a warp Lknitting machine havinga resiliently dis- `placeable tension rod responsive to variations of the -pull of the yarns ilowing over'it; yarntension sustaining means varranged to urge said tension rodyieldingly against the yarns; Vsaid sustaining means including an 'enclosed lcharn- 'ber, means for introducing afluid'under a first predetermined pressure into said chamber, and means associated with said chamber interconnected with said vtension rod and responsive to the pressure of'the fluid in said. chamber to urge said tension rod against said yarns with a force proportional to the pressure ofthefiuid in said chamber; means for controlling operation of the machine; and means responsive to said controlling means for introducing said fiuid under a second predetermined pressure into said chamber.

3. in a warp knitting machine having aresiliently displaceable tension rod responsive to variations of the pull of the yarns flowing overit; yarn tension sustaining means arranged to urge said tension rod yieldingiy against the yarns; said sustaining means including an enclosed chamber, means for introducing a compressiblefluid vunder a first predetermined pressure into said chamber, means associated with said chamber and responsive to the pressureof the iiuid therein, and linkageimeans interconnectingsaid pressure responsive meansand said tension rod: means for controlling operation of the machine; and means responsive to operation ofsaidcontrolling means for introducing said uidundena secondpredetermined pressure into said chamber.

4. in a warp knitting machine having a resiliently displaceable tension rod-responsive to variations of the pull ofthe yarns owing over it; yarn tension sustaining means arranged to urge said tension rod yieldingly against the yarns; said sustainingmeans including an enclosed-chairber, means for introducing a fluid under a first predetermined pressure into said chamber, means associated with said chamber and responsive to the pressure of the iiuidl therein, and connections interconnecting said pressure responsive means and said tension rod; means for controlling operation of the machine; and means responsive to operation of said controlling means for introducing said iiuid under a second predetermined pressure higher than said first predetermined pressure into said. chamber.

5. in a warp knitting machine having a resiliently displaceable tension rod responsive to variations of the pull of the yarns owing over it; yarn tension sustaining means arranged to urge said'tension rod yieldingly against the yarns; said sustaining means including an enclosed chamber, means for introducing a uid under a first predetermined -pressure into said chamber, a piston member associated with said chamber and responsive to the pressure of the fluid therein, and. linkage means interconnectingsaid piston member and said tension rod; means for controlling operation of the machine; and means responsive to operationof said controllingzmeans' for introducing said liiuid under a second predetermined vpressure'higher `thansaidfiirst predetermined pressure intosaidschamber.

6. iin arwarp knittingfmachine having a resiliently displaceable/tension rod responsive to variations-of the pull :of the yarns flowing-over it; yarn tension sustaining-means yassociated therewith .for urging `said tension rod in the yarn tensioning direction; said `sustaining means including a cylinder, means for introducing .a fluid under a first predetermined pressure -nto said cylinder, a piston slidably mountedin said-cylinder, and linkage means interconnecting saidpistonand said tension rod whereby said tension rod is urged against said yarns with a force proportional to the-pressure of the fluid in said cylinder; means for .controlling operation of `the machine; and means responsive-to operationiofsaid controlling means for introducing said fluid -under a-second predetermined pressure higher-than said first predetermined pressure into said cylinder.

7. `In a warp knitting machine having'a resiliently displaceable tension rod-responsive tovariations of the pull of the yarns fiowing-over it;yarn tension sustaining means associated Vtherewith yurging said tension rod against the yarnsgsaidsustaining means including an enclosed chamber,rneans for `introducing affluid'under-a first predetermined vpressure into said chamber, means associated with said chamber and responsive to the pressure of the uid therein, and lconnections interconnecting said pressure responsive means andl said'tension rod;.control means for starting and stopping the machine; and means responsive to the stop operation of said'control means for introducing said fluid under a second rpredetermined pressure higher than said iirstpredeterminedpressure into said chamber.

'8. ina warp knitting machine having a resiliently dis- -placeable tension rod responsive to variations of the pull ofthe yarns iiowing ro.ver-it; yarn tension sustaining vmeans associated therewith urging said tension rod against the yarns; said sustaining means including an enclosed chamber, means for introducing a liiuid under a first predetermined pressure into said-chamber, means associated with said .chamber `and responsive to the pressure of theuid therein, and 'linkage means interconnecting said pressure responsive means and said tension rod whereby said tension rod exerts va `first tensioning force 011 said'yarns'in the yarn tensioning direction, said first force being proportional to said firstjpredetermined pressure; powerrmeans fordriving said machine and means for controlling said kpower'means to start and stop the machine; and means responsive to the stop operation of said controlling means for rintroducing said fluid under a second predetermined pressure 'higher than said first predetermined pressure into said chamber whereby said tension rod exerts a second tensioning force greater than said first force on said yarns.

J9. In a warp knitting machine having aresiliently displaceable tension rod over .which .the yarns `iiow toward the knitting devices, said tension rod being responsive to variations ofthe pull 'of the yyarns flowing over it; yarn tensionsustaining means associated therewith urging saidtension rod against the yarns; said sustaining rmeans including'an enclosed chambenrst fluid control means for-introducinga liuid under a first predetermined pressure into said chamber, `means associated with said chamber `and responsive yto the vpressure of the iiuid therein, and connections interconnecting said pressure responsive means and said tension rodwhereby said tension rod exerts-a rsttensioning force lon said yarns in -the yarn tensioningdirectiori,` said first force being proportional to said firsty predetermined pressure; power -meansfohdriving said machine and means for control- -lingsaid 'power means-to start and vstop the machine; -second fluid control means responsive -to the stop operation of said controlling means for introducing said uid `under a -second vpredetermined ,pressure yhigher than said -firstpredetermined pressure Ainto said chamber whereby saidtension rod exerts asecond tensioning force greater than-saidfirst tensioning force on -said yarns; and means responsive to the start 'operation'ofsaid controlling means for rendering saidiirst fluid control means operative and said second fluid control means inoperative whereby the -iiuid pressure .fin said chamber is `returned to said first predetermined value thereof.

1l0. `in awarpknitting machinerhaving a resiliently displaceable.tension'rod.overwhich the yarns 4flow toward `the. knitting devices, `said .tension rod ibeing responsive to :variations of the pull -of `the lyarns iiowing over it; zyarn l tension sustaining: `means associated therewith urging said tensionsrrod.againstithe` yarns; said ksustaining 9A means including an enclosed chamber, a first fluid colitrol means for introducing a uid under a first predetermined pressure into said chamber, means associated with said chamber and responsive to the pressure of the fluid therein, and connections interconnecting said pressure responsive means and said tension rod whereby said tension rod exerts a first tensioning force on said yarns in the yarn tensioning direction, said first force being proportional to said first predetermined pressure; power means for driving said machine and means for controlling said power means to start and stop the machine; second uid control means responsive to the stop operation of said controlling means for introducing said liuid under a second predetermined pressure higher than said first predetermined pressure into said chamber whereby said tension rod exerts a second tensioning force greater than said first tensioning force on said yarns; and means responsive to the start operation of said controlling means for rendering said first fluid control means operative and said second fiuid control means inoperative whereby the fluid pressure in said chamber is returned to said first predetermined value thereof; said controlling i means including a manually operable device, means for delaying the effect upon said power means of a stop operation of said manually operable device, and means for delaying return of fluid pressure in said chamber to said first predetermined value thereof upon a start operation of said manually operable device.

ll. In a warp knitting machine having a yarn tensioning rod over which the yarns flow toward the knitting devices, means for movably supporting said rod, power means for driving said machine and means for controlling said power means to start and stop the machine, the combination of pressure responsive means for imparting a resilient force to said rod supporting means thereby to apply a corresponding tension to the yarns, said pressure responsive means comprising a cylinder, a piston slidably mounted in said cylinder and connections from said piston to said supporting means, means for introducing a fiuid under a rst predetermined pressure into said cylinder whereby said pressure responsive means imparts a first predetermined resilient force to said rod supporting means, and means responsive to the operation of said controlling means for applying a second predetermined resilient force greater than said first force to said rod supporting means, said latter means comprising means for introducing said uid under a second predetermined pressure into said cylinder.

12. In a warp knitting machine having a yarn tensioning rod over which the yarns flow toward the knitting devices, means for movably supporting said rod, power means for driving said machine and means for controlling said power means to start and stop the machine, the combination of pressure responsive means for imparting a resilient force to said rod supporting means to apply a corresponding tension to the yarns, said pressure responsive means comprising a cylinder, a piston slidably mounted in said cylinder and connections from said piston to said supporting means, means for introducing a fluid under a first predetermined pressure into said cylinder whereby said pressure responsive means imparts a first predetermined resilient force to said rod supporting means, and means responsive to the stop operation of said controlling means for applying a second predetermined resilient force greater than said first force to said rod supporting means, said latter means comprising means for introducing said uid under a second predetermined pressure into said cylinder, said controlling means including a manually operable device and means for delaying the effect upon said power means of a stop operation of said manually operable device.

13. ln a warp knitting machine having a yarn tensioning rod over which the yarns flow toward the knitting devices, means for movably supporting said rod, power means for driving said machine and means for controlling said power means to start and stop the machine, the combination of pressure responsive means for imparting a resilient force to said rod supporting means to apply a corresponding tension to the yarns, said pressure responsive means comprising a cylinder, a piston slidably mounted in said cylinder and a rigid connection between said piston and said supporting means, means responsive to a start operation of said controlling means for introducing a fiuid under a firstl predetermined pressure into ,Said cylinder whereby sa1d pres- 10` sure responsive means imparts a first predetermined resilient force to said rod supporting means, and means responsive to a stop operation of said controlling means for applying a second predetermined resilient force greater thanl said first force to said rod supporting means, said latter means comprising means for introducing said iiuid under a second predetermined pressure into said cylinder, said controlling means including a manually operable device, means for delaying the eect upon said power means of a stop operation of said manually operable device and means for delaying introduction of fluid under said rst predetermined pressure into said cylinder upon a start operation of said manually operable device.

14. ln a warp knitting machine having a resiliently displaceable tension rod responsive to variations of the pull of the yarns flowing over it, rotatable means for supplying yarns to the knitting instrumentalities of said machine, and normally operative braking means for preventing rotation of said rotatable means; yarn tension sustaining means for urging said tension rod against the yarns; said sustaining means including an enclosed chamber, means for introducing a fluid under a first predetermined pressure into said chamber, means associated with said chamber and responsive to the pressure of the fluid therein, and connections from said pressure responsive means to said tension rod; means for controlling operation of the machine; means responsive to said controlling means for introducing said fluid under a second predetermined pressure into said chamber; and connecting means intercoupling said connections and said braking means for releasing said braking means in response to pull exerted on said yarns by the knitting instrumentalities of said machine; said connecting means being arranged to release said braking means for a time interval related to the supply of yarn on said rotatable means.

l5. ln a warp knitting machine having a resiliently displaceable tension rod responsive to variations of the pull of the yarns flowing over it, rotatable yarn carrying reels for supplying yarns to the knitting instrumentalities of said machine, and normally operative braking means for preventing rotation of said reels; yarn tension sustaining means for urging said tension rod against the yarns; said sustaining means including an enclosed chamber, means for introducing a iiuid under a first predetermined pressure into said chamber, means associated with said chamber and responsive to the pressure of the duid therein, and linkage means interconnecting said pressure responsive means and said tension rod; means for controlling operation of the machine; means responsive to operation of said controlling means for introducing said fluid under a second predetermined pressure into said chamber; and connecting means intercoupling said linkage means and said braking means for releasing said braking means in responsive to pull exerted on said yarns by the knitting instrumentalities of said machine; said connecting means being arranged to release said braking means for a time interval related to the supply of yarn on said reels.

16. In a warp knitting machine having a resiliently displaceable tension rod responsive to variations of the pull of the yarns flowing over it, rotatable yarn carrying reel means for supplying yarn to the knitting instrumentalities of said machine, and normally operative braking means for preventing rotation of said rotatable reel means; yarn tension sustaining means for urging said tension rods against the yarns; said sustaining means including a cylinder, a piston slidable within said cylinder, means for introducing a fluid under a first predetermined pressure into said cylinder, and linkage means interconnecting said piston and said tension rod; means for controlling operation of the machine; means responsive to operation of said controlling means for introducing said fluid under a second predetermined pressure into said chamber; and a connecting mechanism intercoupling said linkage means and said braking means for releasing said braking means in response to pull exerted on said yarns by the knitting instrumentalities of said machine; said connecting mechanism and said sustaining means being arranged to release said braking means for a time interval generally inversely proportional to the supply of yarn on said rotatable reel means.

17. In a warp knitting machine having a yarn tensioning rod over which the yarns ow toward the knitting devices, means for movably supporting said rod, power means for driving said machine, means for controlling 12.1 said power meansv to start. andstopvthe machine, rotate able means for supplyingy yarn to the knitting devices of said machine, and normally operative brakingmeans for preventing rotation of i saidg rotatable means,.the, combination of pressure-responsive. rneansfor impartingre silientforceto said rod supporting meansttoy apply afcorresponding tension to the yarns, saidpressureresponsive means comprising a cylinder,y a pistonl slidably mounted in said cylinder and connectionsvfrom'- saidlpstonltovsaid.

supporting means, means for introducingl a compressible fluid under a first predetermined` pressure into; said cylinder whereby said pressure responsive means imparts afirst predeterminedy resilient force to saidv rod supporting means, means responsive: to the operation of said controlling means for applying a second. predetermined. re silient force greater than said rst forceto said'rod supporting means, said. latterl means comprising means for yarns by said knittingdevices, saidllinkage means being disposedfrelativeto said supporting. means and to said pressure responsive means whereby said braking means is released for a time interval generally inversely proportional to the supply of yarns on said. rotatable means.

References Cited in. the le of this patent UNITED STATES PATENTS Number Name Date 2*,305-,420 Herard. Dec. 15, 1942 2,43`0Q022. Lambach Nov. 4, 1947 2,539,296 Clentimack Jan. 23, 1951 

